Flotation apparatus



Feb. 27, 1968 R. D. HAWKINS FLOTATION APPARATUS 4 Sheets-Sheet 1 Filed Dec. 29, 1965 FIG. 2B

C 2 G F INVENTOR. Robert D. Hawkins BY ,4

ATTOR N EY WITNESS w/ Feb. 27, 1968 R. D. HAWKINS 3,370,562

FLOTAT ION APPARATUS Filed Dec. 29. 1965 4 Sheets-Sheet 2 FIG. l2

FIG. 3

INVENTOR. Robert D. Hawkins 7 BY WITNESS W' v ATTORNEY Feb. 27, 1968 HAWKlNS 3,370,562

FLOTATION APPARATUS Filed Dec. 29, 1965 4 heet -She t 5 BU BUM FIG. 6

IN VENTOR Robert D. Hawkins BY NES M P. Q

ATTORNEY 4 Sheets-Sheet 4 R. D. HAWKiNS FLOTAI'ION APPARATUS Feb. 27, 1968 Filed Dec. 29, 1965 M Q Q a Q U A vm 0m 0w om/ 0 0m INVENTOR. ROBERT D- HAWKINS BY ATTORNEY United States Patent 3,370,562 FLOTATION APPARATEJS Robert D. Hawkins, R0. Box 99, Greenlawn, N.Y. 11744) Filed Dec. 29, 1965, Bar. No. 517,349 Claims. Il. 114-67) ABSTRACT OF THE DISLOSURE A stabilized air cushioned vessel is described as having an open bottomed hull. The sides of the hull are so shaped that the center of buoyancy always shifts in a way to keep the vessel upright. As indicated, the hull sides are designed to have submerged inner surfaces that have areas that are nearer the vessel center-of-gravity than freeboard surfaces.

This invention relates in general to fioatable structures, and in particular provides an improved form of bull therefor which works to stabilize itself in response to and as a result of the very forces tending to unstabilize the hull.

Basically the invention provides an open inverted hull that so captures a large volume of air (under relatively slight pressure e.g. .6 lbs. above atmospheric) between the water line and a deck supported by the hull that the center of gravity of the overall structure is substantially well above the water line. While admittedly such a configuration is ordinarily considered unstable and will readily flip-over and sink in response to even very slight forces acting thereupon, nevertheless by suitably designing the sides of the hull, the craft center of buoyancy can be constantly shifted with such forces-not in a way that encourages dipping and ultimate sinkingbut in a way that counteracts the tendency of the craft to invert. This aspect of the invention will be described in detail later.

A second aspect of the invention relates to a form thereof which readily lends itself to such uses as sea platforms and the like, e.g., as is often employed in off-shore drilling for oil. Typical of present practice here is to float a large platform structure to the anchoring location, and then at a time when the sea state is reasonably calm, jackingup the whole platform by means of expensively designed and complicated support legs, using the ocean floor as a base for the legs. Rather than adopt this conventional form of sea platform, the present invention proposes the use of a platform or deck supported by a hull as briefly described above, but in which the hull may take the form of a removable skirt, preferably of an elastic material for wave isolation purposes. To the platform or deck, vertically positionable anchoring stilts are secured, whereby once the platform has been floated to its anchoring location by means of the hull, and the stilts have been lowered for anchoring and support purposes, the hull skirt may be evacuated or even removed to effect a sea platform, and this without jacking equipment.

A third aspect of the invention relates to a presently preferred form of hull skirt, i.e., one which is adjustable to accommodate different conditions of flotation, e.g., when the hull respectively is and is not being driven across the surface of the sea. As to this third aspect of the invention, the hull skirt is provided with an extendable portion which when extended into the water, increases the vertical dimensions of the hull and prevents leakage of the captured volume of air. For hull mobility however the extendable hull position may be raised to a shallow depth to prevent drag, and to encourage planing.

A principal object of the invention is to provide an improved form of hull design.

Another object of the invention is to provide a fioatable structure that is supported by a captured volume of air.

Another object of the invention is to provide a fioatable structure having a center of gravity above the water line and an inverted open hull having sides so disposed that the center of buoyancy of the structure always positions to counter any tendency of the hull to invert.

Another object of the invention is to provide a fioatable structure having an inverted open hull and a deck supported by the hull, such hull being removably secured to the deck.

Another object of the invention is to provide an improved hull configuration that not only is exceedingly stable, but which also isolates members supported by said hull from wave disturbances and the like.

Another object of the invention is to provide an inverted open hull structure, the vertical dimensions of which are adjustable for different conditions of flotation. The invention will be described with reference to the figures wherein:

FIG. 1 is a schematic presentation of one embodiment of the invention,

FIGS. 2A through 2D are diagrams useful in describing the concepts of this invention,

FIG. 3 is a view showing a presently preferred hull design according to the invention,

FIG. 4 is a view showing a feature of interest that is employed in the presently preferred hull design of FIG. 3,

FIGS. 5 and 6 depict the presently preferred hull respectively stationary and moving,

FIGS. 7 through 10 show how a hull according to the invention may be employed to effect a sea platform,

FIG. 11 is a view showing a boat supporting stilt as may be employed with the invention, and

FIG. 12 is a sectional view showing another embodiment of the invention.

Referring to FIG. 1, the presently preferred embodiment of the invention is shown having a deck 10 with an opening 12 therein. The deck 10 is preferably of a material that is impervious to air. An air pump 14 (which preferably is automatically controlled with respect to a pressure reference as is well known in the art) within a walled compartment 16 is adapted to blow air into a chamber 18, the sides of which constitute an open inverted hull 25 The hull 20 is secured to the deck 10 in as close to an airtight manner as possible, and is required for the principal feature of the invention, the sides of the hull 20 make an acute angle with the normal water line 21, being of such form that the sides preferably gradually become more and more acute with respect to the water surface. This latter aspect is desirable since gradually sloping sides compromise between those which are strictly vertical (for virtually complete isolation against the vertical force of waves) and those which are strictly horizontal (ideally the most preferable for stability purposes). The compartment 16 in which the blower 14 contains is provided with a valve 22 that may be adjusted by means of a stern member 24 to exhaust air from the interior of the hull chamber 18. The deck 19 so supports a network of cabins 26, having a topside deck 28, that the craft center of gravity C.G. is substantially well above the normal water line 21. The water line 29 within the open hull 20 is well below the line 21 because of air pressure within the hull chamber 18. The motor 30 for propelling the craft secures to and is rigidly supported by the deck 10.

Reference should now be had to the series of illustrations that constitute FIG. 2, whereby an explanation is given as to why a craft employing the instant techniques has been found to be extremely stable. First off, illustrations A and B, while depicting an open inverted hull that is not in conformity with the invention, are nevertheless useful in emphasizing the concepts of the invention. In FIG. 2A a craft with vertically sloping hull sides 20 is shown in level attitude, its center of buoyancy being on the same vertical as its center of gravity. With a slight unsettling force applied to the craft (FIG. 2B), it starts to rotate about its center of gravity, whereby the captured volume of water X is pushed rightward (looking at FIG. 2) by the sides of the hull 2%. Hence, it is seen that the craft center of buoyancy (i.e., the center of gravity of the displaced volume of water) is shifted rightward as the craft rotates about its own center of gravity, with attendantly the craft flipping over and sinking like an inverted water glass in a tub'of water.

Conside. now a hull according to the invention (FIG. 2, illustrations C and D), viz one with hull sides that slope acutely into the water. Here, when the craft is forced from a level attitude (FIG. 2C) to that shown in FIG. 2D, the captured volume of water X and the craft center of buoyancy are movednot rightwardbut leftward. This can be appreciated from the FIG. 2D which shows the left side of the sloped hull 20 entering and scooping (not pushing) the captured water X whereby the center of buoyancy shifts leftward. As far as the right-hand side of the hull 20 is concerned, this (because of its slope) cuts through the water like a knife edge, and therefore never pushes on the water. In other words, the water adjacent to the right-hand side of the hull spills off such side and, in bootstrap fashion, flows onto the left-hand side of the hull. Since the craft center of buoyancy moves leftward as the left-hand side of the craft tends to sink deeper into the water, a stabilizing counter-force is created by the craft itself, whereby the craft attitude is kept level, a principal object of the invention being thus obtained.

Reference should now be had to FIGS. 3 and 4 which together show the details of a presently preferred form of hull design. A resilient (hull) skirt 40, as might for example be formed from rubberized nylon, secures to the deck by means of bolts 42 in sufficiently airtight manner. When inflated, the hull 40 balloons outward so that its part 44 acutely cuts the water, such ballooning being made possible by means of plural hull support poles .46 which are stationed generally circumferentially within the interior of the hull. Each pole 46 at one end secures to the underside of the deck 10 by means of a flexible coupling 48, and the couplings 48 in combination with the flexible hull itself substantially eliminate any tendency of the craft to respond to high frequency wave disturbances. Each pole 48, at its other end, secures to the hull skirt 40; in addition, respective cables 50 sceure those support pole ends to the deck 10. The walls of the hull 40 are thus prevented from substantial lateral motion as the hull is inflated, whereby the hull part 44 is forced to assume an acute relationship with the line of the water.

-As shown in FIG. 4, the hull .part depicted within the dashed line 52 of .FIG. 3 has a cable 54 that secures within a substantially airtight juncture 55 of the hull part 44 and a hull part 56. In the hull regions 58, the

support poles 46 are adapted to be .pivotally secured. A weighted ring .6050 secures to the base of the hull part 56 that that part ordinarily extends into the water. If

desired, the part 56 may be raised by means of cables 62 that are spatially aligned with the poles 46 and the cables 50. That is, the extendable hull part 56 may be 4 essary detail) the modes of flotation when respectively the craft of the instant invention is adapted for use as a sea platform, and for substantial mobility with minimal drag.

In FIG. 5, the vertical dimension of the hull has been extended as for example when the internal hullrcables 62 secure to the hasps 66. As noted above, this is the sea platform mode and has the advantages of being least susceptible to the loss of air from within the hull chamber 18. That is, for air to escape from within the hull of FIG. 5, as a result of rolling (or pitching), would require the roll angle to be in excess of the angle an essentially remote possibility as discussed above re FIG. 2. (Were the angle of roll to be greater than the angle however,-the air pump 14 would quickly replace the quantity of lost air.) In addition, when the sea state is such that the hull sits atop the crests of, for example, a pair of waves, the extended hull portion 56 assures that there is minimal loss of air, i.e., the opening of the hull bottom is always immersed.

In FIG. 6, the vertical dimension of the hull 20 is shown shortened, as for example by securing the internal hull cables 62 to their respective 'hasps 64; in addition,

the hull is here presumed propelled in a direction D. By raising the hull part 56 substantially out of the water,

drag (obviously) is kept minimal, a first effect necessary to good mobility. Secondly, because of such relatively high mobility, the craft has an improved tendency to plane (further decreasing drag), and to assist such planing the raised part 56 itself contours to augment the lift forces on the craft. See FIG. 6 which shows the lift force F acting on the craft bow, and created as the craft cuts through the water W A small aft lift force F results from water W within the raised part 56 continually washing against that part. When moving, the craft of FIG. 6 rides well out of the water drawing less than 10 inches of water though weighing 60,000 pounds.

With reference to FIGS. 7 to 10, the sea platform feature of the invention will now be-described: FIG. 7 shows the instant boat prior to launching, standing (on circumferentially located stilts to be described presently) near the shore line, at low tide, and with the resilient hull 40 completely deflated. The stilts 80 (see FIG. 11) each comprise a hollow casing 82 having a weighted telescoping leg member 84. The-member 84 secures by means of a hook 86 to a nylon cable 87 that winds on a winch 88. The winch 88 is provided with a crank 90 having a cooperating handle 98 that may be slidably locked in a casing hole 92 to hold the weighted leg member 84 in .place against its downward force. Secured to the casing 82 is a leg clamp 94 having a hole 96 that is slightly larger than the outer diameter of the leg member 84, and which leg member is slidably contained in the hole 96. Locking the leg member 84 against upward movement is attained by the natural wedging of the leg member 84 against the sides of the hole 96 in response to an off-axis upward force. Universally pivotally secured to the end of the leg member 84 is a foot piece 98 which is adapted to orient in accordance with the footing.

As the tide moves in, the hull 40 of the unlaunched boat submerges partially, thereby trapping some air within the chamber portion 18 and readying the hull 40 for flotation, which fact is achieved by turning on the pump 14 (FIG. 1) and causing the hull. 40 to balloon as shown in FIG. 8. With the hull sides ballooned, the stilt legs 84 are raised by means of the winches 88 and their cooperating cranks 90 (FIG. 9), whereby the boat becomes mobilely floated on the captured volume of air Within its chamber 18. See FIG. 6. At the anchoring location, the stilt legs 84 are lowered, by releasing the winches 88 from their respective locked positions, whereby the boat becomes fixedly supported by means of its stilts 80, the feet pieces 98 of the stilts 80 assuming the contours of the ocean floor. Now the hull skirt may be deflated, by opening the exhaust valve 22, after which time the hull may be removed from its deck (see FIG. 10), thereby eflecting a sea platform that is clear of tides, waves, etc., without need for jacking equipment, a principal object of the invention being thus achieved.

While the invention has been described in its presently preferred forms, it is to be realized that the words which have been used are words of description rather than of limitation, and that many changes to the instant embodiments may be made without departing from the true scope and concept of the invention. For example, it would be well within the purview of the invention to employ a doughnut-shaped hull, cross section of which is shown in FIG. 12. The parts depicted on FIG. 12, which relate to respective parts of FIGS. 1, 3, etc., have the same reference characters as indicated on those figures but to distinguish the FIG. 12 characters, primed notations have been employed.

What is claimed is:

1. Flotation apparatus comprising an open bottomed hull for use in a flotation fluid, deck means supported by said hull, said hull having sides the inside surfaces of which are so sufficiently acute with respect to the surface of said flotation fluid that said sides fold inwardly toward the center of said hull to cause the center of buoyancy of said flotation apparatus to shift toward that side of said flotation apparatus which is deepest in said flotation fluid, said sides having submerged areas which are of lesser distances from the center of gravity of said apparatus than are the freeboard surfaces, and means for applying under pressure fluid that is less dense than the flotation fluid between said deck means and said hull,

said hull being so shaped that said less dense fluid is displaced downwardly substantially within the confines of said bull in proportion to the pressure of said less dense fluid, said sides being so adapted that their respective lowermost points are substantially always below the surface of said flotation fluid, said deck means and said hull being substantially impervious to said less dense fluid.

2. The apparatus of claim 1 wherein the sides of said hull have slopes that gradually change acutely with respect to the surface of the flotation fluid.

3. The apparatus of claim 2 wherein said hull is of a flexible material.

4. The apparatus of claim 1 wherein said hull is of a flexible material.

5. The apparatus of claim 1 wherein said means for applying a less dense fluid under pressure in an automatically controlled airpump for keeping the pressure within said hull at a predetermined pressure reference.

References Cited UNITED STATES PATENTS 3,040,688 6/1962 Gram 11467 3,134,452 5/1964 Latimer-Ncedham l-7 3,258,080 6/1966 Williams et a1. -7 3,268,022 8/1966 Gustafson 180-7 ANDREW H. FARRELL, Primary Examiner. MILTON BUCHLER, Examiner. 

